Microphones are used to obtain a voice signal from a speaker. Once obtained, the signal can be processed in a number of different ways. A wide variety of functions can be provided by today's microphones and they can interface with and utilize a variety of different algorithms.
Voice triggering, for example, as used in mobile systems is an increasingly popular feature that customers wish to use. For example, a user may wish to speak commands into a mobile device and have the device react in response to the commands. In these cases, a programmable digital signal processor (DSP) will first use a voice activity detection algorithm to detect if there is voice in an audio signal captured by a microphone, and then, subsequently, analysis is performed on the signal to predict what the spoken word was in the received audio signal. Various voice activity detection (VAD) approaches have been developed and deployed in various types of devices such as cellular phone and personal computers.
In the use of these approaches, power consumption becomes a concern. Lower power consumption gives longer standby time. For today's smart-phones (in particular), the use of power is a key parameter. Unfortunately, present approaches of operating microphones use and waste much power. This has resulted in user dissatisfaction with these previous approaches and systems.
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